The present invention relates to a frequency synthesizing device having an input access for a digital code which defines the frequency to be synthesized and an accumulator circuit for successively counting the digital codes, in the form of numbers, in time with signals of an accumulation clock.
A device of this type finds important applications, especially in the field of data transmission where the carrier frequency of the data is to be established with very great precision.
A device of this type is known from U.S. Pat. No. 4,514,696.
This device produces an output frequency f.sub.u based upon an N-bit digital code C: EQU f.sub.u C.times.F.sub.R /2.sup.N
where F.sub.R is the frequency of the signals of a reference clock preferably formed, as is common practice, by a quartz crystal. From this formula is derived the variation step .DELTA.f given by the formula: EQU .DELTA.f=F.sub.R /2.sup.N
while admitting that the variation of C is unitarian.
In the applications considered above, in which the device is used in a phase locked loop for restoring the carrier, this variation step is considered very important.